Bollettino valanghe

Northwest Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Westerly winds and accumulating snow are building new wind slabs on the lee sides of terrain features. Careful terrain and snowpack evaluation will be necessary to manage this new avalanche problem at near and above treeline elevations. There is a further possibility that destructive avalanches could release deeper into the snowpack on old, persistent weak layers, such as this skier-triggered avalanche that occurred on a cross-loaded slope just outside of our forecast area in Marble. Slab avalanche concerns are less common in wind-sheltered terrain at lower elevations. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    The storm is just getting going during the early morning hours. Gusty westerly winds will load the new snow onto the lee sides of terrain features and build a new wind slab avalanche problem. Carefully evaluate this instability below ridgelines and cross-loaded terrain features, or consider routing around that specific terrain. 

    An example of an old wind slab that was human triggered last weekend on Coneys. (3/15/2025)

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    In the past week, we've observed large to very large slab avalanches breaking on weak layers in the upper snowpack and near the ground at higher elevations.  Feedback on the problem will be variable and infrequent. These issues are most concerning on wind-loaded terrain on colder, shadier aspects highlighted by the persistent slab rose.  Avoid steep, wind-loaded slopes and wind-affected terrain with variable snow depths to reduce your risk.   Persistent slab instabilities are more isolated below treeline; stay alert on very steep or unusually shallow slopes. Southerly aspects typically lack the problem.  

Avalanche Discussion

Catch up on the weekly summary for all the recent conditions. You can read the text verson here, or view the video version here.

Here is a link to the documented human-triggered persistent slabs in the last week. The primary layer of concern can be found in the upper snowpack, and was buried around March 13th. This layer of small facets has been the most reactive on the Northeast quadrant of the compass. Where these facets are buried by several feet of snow, they have shown notable improvements as they continue to gain strength. This observation finds one of those examples.  Now, for the next few days, the focus or area of concern will begin to switch to where these facets were only buried by about a foot of snow and haven't gained as much strength. Last week, those areas didn't typically have enough of a slab to produce an avalanche, and now the accumulating snow is changing those conditions. Larger triggers in the last week, such as cornice falls, or heavy wind-loading, have also produced very large avalanches releasing on old weak layers at the middle or at the bottom of the snowpack. Prior to the current wind slabs that are forming, the more reliable options for stepping out into steeper alpine terrain are on southerly aspects, where our March weak layers were typically cooked off, and our early season weak layers saw meltwater.

Although percistent weak layers exist on shady (northerly) aspects below treeline (ex. Brush Creek), the snowpack and avalanche activity have been relatively quiet this week.  If you're riding in steep, wind-sheltered areas with a deep and consistent snowpack, it's worth pausing to evaluate how thick and sensitive the March slab is over small-grained facets buried earlier this month. Lingering instabilities would most likely be on very steep, unsupported terrain features, breaking 1 to 2 feet deep.   If you're riding in wind-sheltered areas in the Southeast Mountain forcast area, keep in mind there is isolated potential for an avalanche to break several feet deep on weak layers near the ground.

Wet avalanche concerns will begin tomorrow and then grow through the coming week.

Events:  Stop by our next trailhead day this Sunday at Kebler TH.  We'll be grilling brats and celebrating the winter season!

Regioni coperte